Psion (thing)

Created in about 1984. It had an alaphabetic keyboard (non QWERTY) and a one line LCDdisplay. It had sliding plastic cover to protect the keyboard.

The Organiser II

An updated version of the Organiser. Typicaly it had 64k of memory and a 4 line display, although some versions had a 2 line display. Famed for being rugged they are still in use in some places for datacollection. (For example within Psion I've seen them used within their repair and service depot to keep track of items)

The Series 5 wasn't really much more than an overhaul of the Series 3. It was available from 1997. It had a touch screen, a new type of keyboard (real keys vs. the Series 3's rubber keys), a mutli-tasking 32bit OS and a standard IrDA port for connecting to computers and mobiles. It came with lots of software and had wireless internet access.

Released in June 1999. The 5mx had optimised software and an enhanced OS (EPOC v5). It came with 16mb of memory and had a faster processor. It also had a Java Virtual Machine (JVM) for browsing java-enabled web sites.

Released in October 1999, four months after the 5mx. The Revo is similar to the 5 Series. The main differences are that it is smaller, with a lower-res screen and smaller keys. It also featured built in rechargable batteries and no CF card slots. It has 8mb of RAM and a IrDA port for browsing the internet over a mobile phone.

Parts of this are based on information from http://3lib.ukonline.co.uk/historyofpsion.htm
The majority of it, however, is based on my experience of working with Psions and having worked (briefly) for Psion.